Arrangement for guiding the direction of feed material on sewing machines



R. DOBNER ET AL ARRANGEMENT FOR GUIDING THE DIRECTION OF Feb. 17, 1970 FEED MATERIAL ON SEWING MACHINES 2 Sheets-sheaf. 1

Filed June 3. 1968 mseaaer 32/2 R. DOBNER ET AL ARRANGEMENT FOR GUIDING THE DIRECTION Feb. 17, 1970 OF 3,495,558

FEED MATERIAL 0N SEWING MACHINES- 2 Sheets-Sheet 2 Filed June 3, 1968 United States Patent 3,495,558 ARRANGEMENT FOR GUIDING THE DIRECTION OF FEED MATERIAL 0N SEWING MACHINES Reinhold Dobner, Kaiserslautern, Gunther Gross, Stockborn, and Herbert Weuz, Kaiserslautern, Germany, assignors to G. M. Pfatf AG, Kaiselslautern, Pfalz, Germany Filed June 3, 1968, Ser. No. 734,077 Claims priority, application Gesrmany, June 13, 1967,

Int. Cl. nosb 27/16 US. Cl. 1121-211 3 Claims ABSTRACT OF THE DISCLOSURE Background of the invention The invention relates to means for guiding the material being sewed on sewing machines. More in particular the invention is concerned with an arrangement in sewing machines for controlling the direction of feed of the sewing material.

The rational and accurate production of seams following an arcuate course requires special arrangements for guiding the material.

Thus, arrangements are known where the sewing material is stretched in a frame. These frames carrying the sewing material are guided by means of cam disks in the directions of two coordinates. Arrangements of this type are only suitable for the production of larger series or sets of equally shaped work blanks where the requirernent for even appearance of the image of the seam of each blank are strict. Guiding arrangements of this type are only useable, however, for dual needle machines, because the blanks are not turned upon the material carrying plate for producing an arcuate seam, but in feeding steps directed forward and backward longitudinally and transversely while they are always in the same angular position as related to the sewing machine. As a result the two rows of seams would not only change their spacing relative ,to one another, depending on the direction and on the course of the curve, but along stretches they would even cross over one another.

Summary of the invention In accordance with the invention the arrangement for guiding the work blanks is to be so constructed that seams of equally arcuate shape or following an equal arcuate course can be produced on a sewing machine having a single needle as well as on machines that are equipped with two needles. Thus, in accordance with the invention the arrangement for guiding the work blanks is to be constructed in a manner that the work blanks are turned by the guiding members about an axis of rotation whose distance from the location of the stitch formation corresponds at any time exactly to the radius of the arcuate section of the seam line to be sewn. v

In accordance with the invention this is accomplished by intermittently driven feeding members disposed below the work supporting plate in parallel relationship to one c Ce another, with which the size of each feeding step is adjustable for straight forward feed by setting means in an1 inversely constant relationship to a common median va ue.

By the inverse adjustment of the size of each feeding step the feeding speed of the work blanks at the stitch forming location is of equal magnitude when the setting of the stitch length is not changed. With single needle machines the needle stitches are thus at equal distances from one another over the entire course of the seam. With double needle machines the stitch spacings in an arc section are drawn apart or pushed together in the same relationship in which the seam becomes longer or shorter, depending on its location relative to the center point of the curve.

It is advantageous that the feeding of the blank as Well as the guiding of the blank are effected by only one pair of feeding elements, while in addition, the timing of the occurrences of both movements is superimposed so that they take place simultaneously.

The structural design of the setting or adjusting means which engage the gearing of the feeding elements is especially simple. It consists in that an axially displaceable setting shaft is mounted inside the feed or pusher shaft, which in the area of each of the cranks has inclined teeth, the inclination of which extends in opposite directions, and which are in engagement with corresponding counter teeth of the cranks through recesses in the feed or pusher shaft. By these means the arrangement in accordance with the invention can be utilized without change for hand controls and knee fork controls as well as for producing predetermined sewing patterns by means of cam disks and for parallel edge work, and this in cooperation with an arrangement which scans the edge of the material being sewn.

Brief description of the drawings Further advantageous features and details of the invention will become apparent from the following descrip tion of an embodiment of the arrangement in accordance with the invention illustrated in the drawings in which:

FIG. 1 is a front view partly in section showing a double needle sewing machine in accordance with the invention,

FIG. 2 is an enlarged section of the arrangement in accordance with the invention,

FIG. 3 is a perspective illustration of a part of the feeding gear,

FIG. 4 is a perspective illustration of the helical tooth setting shaft with a crank journalled in its guiding slide taken along the section line IVIV in FIG. 5, and

FIG. 5 is a partial section through a crank journalled in its guiding slide with coupling and associated freerunning clutch taken along line VV in FIG. 3.

Description of the preferred embodiment As shown in FIG. 1 the sewing machine comprises a base plate 1, the column 2, the socket 3 and standard 4 with the arm 5 supporting the head 6. The arm shaft 7 is journalled in the usual manner in the arm 5 and is driven at one end 'by way of a cord belt 8 or the like from a main drive shaft 9 journalled in the socket 3 and is operatively connected at its other end with the needle bar 10 inside the head 6. The needle bar is provided with two needles 1-1, 12. The column 2 has a work surface 2a for supporting the material being sewn, such as work blanks.

By means of the main drive shaft 9 which carries a belt pulley 13 at the end projecting from the socket 3, a further cord belt drives the looper shaft 15 journalled in the base plate, which in turn is operatively connected by way of pairs of cone pinions 16, 17 (FIG. 2), and by way of vertically disposed shafts 18, 19 with the two loopers 20, 21 which rotate horizontally in the upper end of the column (FIG. 2).

The drive for the feeding of the work blank is picked up by means of a forked bar 22 from a cam element 23 secured to the main drive shaft 9. The forked bar 22 is coupled with a conventional means 24 for setting or adjusting the stitch and is connected by way of a crank 25 with a feed shaft 26 journalled parallel to the looper shaft 15.

As shown by FIG. 2, there are two slide guides 27, 28 upon the feed shaft 26 in which cranks 29, 30 are journalled that extend transversely of the longitudinal axis of the feed shaft, and which are connected by way of couplings 31, 32 with free-running couplings 33, 34. The coupling shafts 35, 36 of the free-running couplings 33, 34 transfer the movements by means of two pairs of pinions 37, 38 to vertical hollow shafts 39, 40 which concentrically surround the shafts 18, 19. At the upper end of the vertical hollow shafts 39, 40 there are secured two drive wheels 41, 42 with friction layers which are in frictional driving engagement with two vertically rotating feeding elements in the form of feed wheels 43, 44 of annular configuration. The feed wheels 43, 44 are arranged immediately alongside the two needle or stitch holes 45, 46 and mounted for rotation in the manner disclosed in US. Patent 3,066,625.

-In order to obtain an effective force transmission between the work blanks and the feed wheels 43, 44, two roller feet 47, 48 are disposed above the feed wheels and are journalled for free rotation in a frame 50 secured to the presser bar 49.

Alongside the free-running couplings 33, 34 which serve as step switches, additional free-running couplings 51, 52 are arranged upon shafts 35, 36 which serve as return or back stops for the feed wheels 43, 44.

Inside the feed shaft 26, an axially displaceable setting shaft 53 is journalled. This setting shaft has an oblique set of teeth in the area of the two guide slides 27, 28 in the form of a toothed rack (FIG. 4). The direction of inclination of the series of teeth disposed in the area of one guiding slide 27 or 28 is oppositely disposed with respect to the direction of inclination of the other series of teeth. Upon the feed shaft 26 the guide slides 27, 28 are secured by means of clamping slots 54 and screws 55. In these guide slides cranks 29, 30 are mounted for displacement relative to the longitudinal axis of the feed shaft. In the area of the cranks 29, 30, the feed shaft 26 is provided with apertures through which the oblique toothing of the setting shaft 53 is in engagement with corresponding matching teeth of the cranks 29, 30.

In the embodiment illustrated, the setting shaft 53 is connected with control means which are actuated by the operating means. In the base plate 1 a setting lever 57 is pivotally mounted by means of a pin 56, and forms at its other end a pivot joint 59 together with a further pin 58 and the setting shaft 53, while the other end thereof is provided with a handle or a knee link (not illustrated).

In the area of the pivot joint 59, a retaining finger 60 I is provided which is offset in the direction of the joint 59 and whose width corresponds exactly to the part of the setting lever 57 which encompasses the pin 58. Two pressure springs 61, 62 which are arranged on both sides of the joint 59 upon the setting shaft 53, and which support themselves on stationary bearings, press the setting lever 57 and thus also the setting shaft 53 during the idling condition exactly into the center position determined by the arrangement of the retaining finger 60 by way of two pressure disks 63, 64 in engagement with the joint 59.

The arrangement in accordance with the invention operates as follows:

For driving the feed wheels 43, 44 the uniform rotational movement of the cam 23 is converted into an oscillating movement of the feed shaft 26. By means of the adjustment of the stitch setting device 24, the angular deflection of the rotational movement of the feed shaft can be varied. Beginning with the feed shaft 26, the feed drive heretofore common to both feed wheels 43, 44 is shared and is now separately guided on for each feed wheel. The movement of the feed shaft 26 is passed on by way of the cranks 29, 30 and couplings 31, 32 to the free-running or free motion couplings 33, 34 and converted by them into an intermittent movement and transmitted by way of pinion pairs 37, 38 and hollow shafts 39, 40 onto the friction wheels 41, 42 which are in driving connection with the feed wheels 43, 44.

During straight, forward feeding, the setting shaft 53 and setting lever 57 are in the center position determined by the arrangement of the retaining finger 60. In this position, the effective lever lengths of the cranks 29, 30 which extends from the longitudinal axis of the feed shaft to the axis of rotation of the joints formed by the cranks 29, 30 and couplings 31, 32 are of equal magnitude. As a result of the equal lever ratio of the cranks 29, 30, the magnitude of the movement of the feed shaft 26 is transferred without alteration to the free-running or free motion couplings 33, 34 and on to the feed wheels 43, 44 so that they feed the work blank exactly along a straight line.

For sewing curves, the setting shaft 53 is displaced from its center position to the left or to the right, depending on the sense of direction of the curve to be sewed. In this connection, the cranks 29, 30 are displaced in their guiding slides 27, 28 by the oppositely extending inclined directions of the two sets of inclined teeth of the setting shaft 53 also in opposite directions. The effective lever length of one of the cranks, for example 29, and thus also the magnitude of feeding of the corresponding feed wheel 43 is now increased by the same absolute amount by which the effective lever length of the other crank 30 and the feeding length of the other feed wheel 44 is decreased. In this manner the work blank is turned by the feed wheel 43 which effects the larger feed steps about an axis of rotation disposed in the direction of the other feed Wheel 44. In this connection the distance of the said axis of rotation from the location of stitch formation, and thus also the radius of the section of the curve or are depends on the difference of the dimension of the feed steps of the two. feed members 43, 44. Since the setting shaft 53 is continually adjustable within its range of adjustment, any desired arc can be sewn by means of the arrangement in accordance with the invention.

Inasmuch as the axes of rotation of the feed wheels 43, 44 are in a plane with the center lines of the stitch holes 45, 46, the part of the work blank located in the area of the stitch-forming location is always moved during rotation exactly tangentially with respect to the direction of feed. In turn again, spacings are obtained between the two seam lines which always remain the same.

Besides the possibility of connecting the setting shaft 53 with manually operable control means, it can also be guided directly by means of cam disks or with an arrangement for scanning the edge of the work blanks.

Although the arrangement in accordance with the invention may basically be equipped also with two square feed dogs, it is particularly suitable for sewing machines having feed wheels, the drive of which is by way of freerunning couplings which are connected by cranks and couplings with a common feed shaft driven in oscillating fashion. In accordance with a further development of the invention, the cranks are displaceable for changing their lever lengths in guide slides secured to the feed shaft perpendicularly to the longitudinal axis of the feed shaft, and are connected with the setting means which operate in an opposite sense.

Having now described our invention with reference to the embodiment illustrated in the drawings, we do not wish to be limited thereto, but what we desire to protect by Letters Patent of the United States is set forth in the appended claims.

We claim:

1. In a sewing machine, an arrangement for controlling the direction of feed of the material being sewn, said machine having a base, a work surface and a drive shaft, and said arrangement comprising a pair of feeding elements disposed below said work surface and generally parallel relative to one another, intermittently driven feed means disposed in said base and operatively connected to said feeding elements including an intermittently driven feed shaft linked to said drive shaft and a setting shaft concentric with said feed shaft having a pair of oppositely directed setting means, a pair of slide guides each associated with one said setting means and each having a crank, a pair of free running coupling means each connected to one said crank and including a coupling shaft for transmitting feed movements from said feed shaft by said cranks to their couplings and to said feeding elements, and means connected to said setting shaft for axially moving said setting shaft.

2. Arrangement in accordance with claim 1, where said feeding elements are feed wheels and said feed means include vertical shafts having drive wheels at their upper ends below said work surface in engagement with said feed wheels and having pinions at their lower ends and said coupling shafts having pinions in driving engagement with the pinions of said vertical shafts, said slide guides being movable vertically with respect to the axis of said setting shaft to change the relative lever lengths of said cranks in the opposite sense.

3. Arrangement in accordance with claim 2, where said setting shaft is axially movable in said feed shaft, said oppositely directed setting means being teeth in said setting shaft proximate said cranks inclined in opposite directions, said feed shaft having apertures for said teeth and said cranks having corresponding teeth meshing with the corresponding teeth on said setting shaft through said apertures.

References Cited UNITED STATES PATENTS 2,885,983 5/1959 Bennick et al. 1l2211 2,979,745 4/ 1961 Schaefer 112-211 3,382,827 5/1968 Von Hagen 112-209 2,875,716 3/1959 Pinkvoss 112-211 ALFRED R. GUEST, Primary Examiner 

